Archangel of Thune

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Whenever you gain life, put a +1/+1 counter on each creature you control.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on this creature.

Heliod, Sun-Crowned

Indestructible
As long as your devotion to white is less than five, Heliod isn't a creature.
Whenever you gain life, put a +1/+1 counter on target creature or enchantment you control.
{1}{W}: Another target creature gains lifelink until end of turn.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Plains

Gleam of Resistance

Creatures you control get +1/+2 until end of turn. Untap those creatures.
Basic landcycling {1}{W} ({1}{W}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Ranger-Captain of Eos

When Ranger-Captain of Eos enters, you may search your library for a creature card with mana value 1 or less, reveal it, put it into your hand, then shuffle.
Sacrifice Ranger-Captain of Eos: Your opponents can't cast noncreature spells this turn.

Famished Paladin

Famished Paladin doesn't untap during your untap step.
Whenever you gain life, untap Famished Paladin.

Twinblade Paladin

Whenever you gain life, put a +1/+1 counter on this creature.
As long as you have 25 or more life, this creature has double strike. (It deals both first-strike and regular combat damage.)

Ajani, Wise Counselor

+2: You gain 1 life for each creature you control.
−3: Creatures you control get +2/+2 until end of turn.
−9: Put X +1/+1 counters on target creature, where X is your life total.

Cradle of Vitality

Whenever you gain life, you may pay {1}{W}. If you do, put a +1/+1 counter on target creature for each 1 life you gained.

Sunbond

Enchant creature
Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."

Abiding Grace

At the beginning of your end step, choose one —
• You gain 1 life.
• Return target creature card with mana value 1 from your graveyard to the battlefield.

Impassioned Orator

Whenever another creature you control enters, you gain 1 life.

Ajani's Welcome

Whenever a creature you control enters, you gain 1 life.

Ajani's Mantra

At the beginning of your upkeep, you may gain 1 life.

Attended Healer

Whenever you gain life for the first time each turn, create a 1/1 white Cat creature token.
{2}{W}: Another target Cleric gains lifelink until end of turn.

Well of Lost Dreams

Whenever you gain life, you may pay {X}, where X is less than or equal to the amount of life you gained. If you do, draw X cards.

Humming-

Flying
Whenever you attack with two or more creatures,
Augment {3}{W} ({3}{W}, Reveal this card from your hand: Combine it with target host. Augment only as a sorcery.)

Chalice of Death

Chalice of Life

{T}: You gain 1 life. Then if you have at least 10 life more than your starting life total, transform Chalice of Life.

Chalice of Life // Chalice of Death

Recruiter of the Guard

When Recruiter of the Guard enters, you may search your library for a creature card with toughness 2 or less, reveal it, put it into your hand, then shuffle.

Ajani, Caller of the Pride

+1: Put a +1/+1 counter on up to one target creature.
−3: Target creature gains flying and double strike until end of turn.
−8: Create X 2/2 white Cat creature tokens, where X is your life total.

Angel of Destiny

Flying, double strike
Whenever a creature you control deals combat damage to a player, you and that player each gain that much life.
At the beginning of your end step, if you have at least 15 life more than your starting life total, each player Angel of Destiny attacked this turn loses the game.

Celestial Mantle

Enchant creature
Enchanted creature gets +3/+3.
Whenever enchanted creature deals combat damage to a player, double its controller's life total.

Beacon of Immortality

Double target player's life total. Shuffle Beacon of Immortality into its owner's library.

Serra Ascendant

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
As long as you have 30 or more life, Serra Ascendant gets +5/+5 and has flying.

Ajani, Strength of the Pride

+1: You gain life equal to the number of creatures you control plus the number of planeswalkers you control.
−2: Create a 2/2 white Cat Soldier creature token named Ajani's Pridemate with "Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate."
0: If you have at least 15 life more than your starting life total, exile Ajani, Strength of the Pride and each artifact and creature your opponents control.

Answered Prayers

Whenever a creature you control enters, you gain 1 life. If Answered Prayers isn't a creature, it becomes a 3/3 Angel creature with flying in addition to its other types until end of turn.

Light of Promise

Righteous Valkyrie

Flying
Whenever another Angel or Cleric you control enters, you gain life equal to that creature's toughness.
As long as you have at least 7 life more than your starting life total, creatures you control get +2/+2.

Serene Steward

Whenever you gain life, you may pay {W}. If you do, put a +1/+1 counter on target creature.

Angel's Grace

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
You can't lose the game this turn and your opponents can't win the game this turn. Until end of turn, damage that would reduce your life total to less than 1 reduces it to 1 instead.

Ajani Goldmane

+1: You gain 2 life.
−1: Put a +1/+1 counter on each creature you control. Those creatures gain vigilance until end of turn.
−6: Create a white Avatar creature token. It has "This creature's power and toughness are each equal to your life total."

Kor Celebrant

Whenever Kor Celebrant or another creature you control enters, you gain 1 life.

Hallowed Priest

Whenever you gain life, put a +1/+1 counter on Hallowed Priest.

Adorable Kitten

When this creature enters, roll a six-sided die. You gain life equal to the result.

Celestial Unicorn

Whenever you gain life, put a +1/+1 counter on Celestial Unicorn.

Cleric Class

(Gain the next level as a sorcery to add its ability.)
If you would gain life, you gain that much life plus 1 instead.
{3}{W}: Level 2
Whenever you gain life, put a +1/+1 counter on target creature you control.
{4}{W}: Level 3
When this Class becomes level 3, return target creature card from your graveyard to the battlefield. You gain life equal to that creature's toughness.

Valkyrie Harbinger

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of each end step, if you gained 4 or more life this turn, create a 4/4 white Angel creature token with flying and vigilance.

Gideon's Company

Whenever you gain life, put two +1/+1 counters on Gideon's Company.
{3}{W}: Put a loyalty counter on target Gideon planeswalker.

Aerial Responder

Nykthos Paragon

Whenever you gain life, you may put that many +1/+1 counters on each creature you control. Do this only once each turn.

Sanctum of the Sun

(Transforms from Azor's Gateway.)
{T}: Add X mana of any one color, where X is your life total.

Azor's Gateway

{1}, {T}: Draw a card, then exile a card from your hand. If cards with five or more different mana values are exiled with Azor's Gateway, you gain 5 life, untap Azor's Gateway, and transform it.

Azor's Gateway // Sanctum of the Sun

Dawn of Hope

Whenever you gain life, you may pay {2}. If you do, draw a card.
{3}{W}: Create a 1/1 white Soldier creature token with lifelink.

Eternity Vessel

Eternity Vessel enters with X charge counters on it, where X is your life total.
Landfall — Whenever a land you control enters, you may have your life total become the number of charge counters on Eternity Vessel.

A-Cosmos Elixir

At the beginning of your end step, draw a card if your life total is greater than your starting life total. Otherwise, you gain 2 life and scry 1.

Citanul Flute

{X}, {T}: Search your library for a creature card with mana value X or less, reveal it, put it into your hand, then shuffle.

Wayward Disciple

Whenever Wayward Disciple or another creature you control dies, target opponent loses 1 life and you gain 1 life.

Pious Evangel

Whenever Pious Evangel or another creature you control enters, you gain 1 life.
{2}, {T}, Sacrifice another permanent: Transform Pious Evangel.

Pious Evangel // Wayward Disciple

Voice of the Blessed

Whenever you gain life, put a +1/+1 counter on Voice of the Blessed.
As long as Voice of the Blessed has four or more +1/+1 counters on it, it has flying and vigilance.
As long as Voice of the Blessed has ten or more +1/+1 counters on it, it has indestructible.

Soul Warden

Whenever another creature enters, you gain 1 life.

Angel of Grace

Flash
Flying
When Angel of Grace enters, until end of turn, damage that would reduce your life total to less than 1 reduces it to 1 instead.
{4}{W}{W}, Exile Angel of Grace from your graveyard: Your life total becomes 10.

Celestial Convergence

Celestial Convergence enters with seven omen counters on it.
At the beginning of your upkeep, remove an omen counter from Celestial Convergence. If there are no omen counters on Celestial Convergence, the player with the highest life total wins the game. If two or more players are tied for highest life total, the game is a draw.

Luminous Phantom

Flying
Whenever another creature you control leaves the battlefield, you gain 1 life.
If Luminous Phantom would be put into a graveyard from anywhere, exile it instead.

Lunarch Veteran

Whenever another creature you control enters, you gain 1 life.
Disturb {1}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Lunarch Veteran // Luminous Phantom

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Castle Ardenvale

Castle Ardenvale enters tapped unless you control a Plains.
{T}: Add {W}.
{2}{W}{W}, {T}: Create a 1/1 white Human creature token.